• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1526-1531
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• 2008

The objective of this study is to evaluate the loading capacity of lattice girder according to loading position. 3-point flexible strength tests were performed on three types of lattice girder, such as LG-$50{\times}20{\times}30$, LG-$70{\times}20{\times}30$, and LG-$95{\times}22{\times}32$, mainly used in Korea. Two types of loading position for each flexible strength test were used to analyze the behavior of load-deformation. In 3-point flexible strength test, the difference of the average of maximum flexible strength according to loading position had the range from 10% to 33%.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.4
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• pp.113-122
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• 2017

PURPOSE: The purpose of this study was to investigate the comparison of muscle activity and mechanical loading according to the angle of ankle joint during a sit-to-stand (STS) task. METHODS: Thirty-four young participants performed the STS in a randomized trial with the ankle joint at a neutral, 15 degrees dorsiflexion and 15 degrees plantarflexion angle in a fixed sitting posture with the knee in 105 degrees flexion. Muscle activity of the tibialis anterior (TA), rectus femoris (RF), biceps femoris (BF), and gastrocnemius medialis (GCM) was measured, and the parameters calculated in relation to mechanical loading were the STS-time, maximum peak, minimum peak, and total sum of mechanical loading. RESULTS: In the dorsiflexion position, the muscle activity of the TA and GCM showed a significant increase (p<.05), and the STS time, maximum peak and total sum of mechanical loading showed a significant difference compared to that in the neutral position (p<.05). In the plantarflexion position, the muscle activity of the RF and GCM showed a significant increase (p<.05), while that of the TA showed a significant decrease (p<.05) compared to that in the neutral position. And the minimum peak was significantly increased than the neutral position (p<.05), and the maximum peak and total sum of mechanical loading were showed significant difference compared with dorsiflexion position (p<.05). CONCLUSION: These results show that there is a difference in muscle activity and mechanical loading when performing the STS movement according to the change in the ankle joint angle.

• Journal of Dental Rehabilitation and Applied Science
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• v.21 no.2
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• pp.169-182
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• 2005

The purpose of this study was to compare the stress distribution around the surrounding bone according to the splinted and non-splinted conditions on the finite element models of the two implant crowns with the different vertical bone level. The finite element model was designed with the parallel placement of the two fixtures ($4.0mm{\times}11.5mm$) with reverse buttress thread on the mandibular 1st and 2nd molars. As the bone quality, the inner cancellous bone and the outer 2 mm cortical bone were designed, and the cortical and cancellous bone were assumed to be perfectly bonded to the implant fixture. The splinted model(Model 1) had 2 mm contact surface and the non-splinted model(Model 2) had $8{\mu}m$ gap between two implant crowns. Two group (Splinted and non-splinted) was loaded with 200 N magnitude in the vertical and oblique directions on the loading point position on the central position of the crown, the 2 mm and 4 mm buccal offset point from the central position. Von Mises stress value was recorded and compared in the fixture-bone interface in the bucco-lingual and mesio-distal sections. The results were as follows; 1. In the vertical loading condition of central position, the stress was distributed on the cortical bone and the cancellous bone around the thread of the fixture in the splinted and non-splinted models. In the oblique loading condition, the stress was concentrated toward the cortical bone of the fixture neck, and the neck portion of 2nd molar in the non-splinted model was concentrated higher than that of 1st molar compared to the splinted model. 2. In the 2 mm buccal offset position of the vertical loading compared to the central vertical loading, stress pattern was shifted from apical third portion of the fixture to upper third portion of that. In the oblique loading condition, the stress was distributed over the fixture-bone interface. 3. In the 4 mm buccal offset position of the vertical loading, stress pattern was concentrated on the cortical bone around the buccal side of the fixture thread and shifted from apical third portion of the fixture to upper third portion of that in the splinted and non-splinted models. In the oblique loading, stresses pattern was distributed to the outer position of the neck portion of the fixture thread on the mesio-distal section in the splinted and non-splinted models. Above the results, it was concluded that the direction of loading condition was a key factor to effect the pattern and magnitude of stress over the surrounding bone of the fixture under the vertical and oblique loading conditions, although the type with or without proximal contact did not effect to the stress distribution.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.249-251
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• 2006

In this study, a systematic and effective tuning method of the actuator control parameters of the control loading system for aircraft based on control theory is presented. Firstly, to raise the time response of the system, the proportional gain and the integral gain of the velocity control loop is maximized within the range where vibration and noise does not occur. And then the position control loop is composed by getting the transfer function of the control loading system including the velocity control loop. With the root locus of the composed position control loop, the proportional gain of the position control loop that keeps stable transient state and leads good time response of the system is predicted, and the simulations are performed by using the predicted gain. Lastly, the actuator control parameters of actual control loading system are set to the previously obtained gain values. And the experiments to actuate the control loading system are executed. It shows that the tuning method of the actuator control parameter proposed in this study is applied to actual control loading system very well by comparing the results of the experiments with those of the simulations.

• Journal of Technologic Dentistry
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• v.27 no.1
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• pp.105-113
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• 2005

The purpose of this study is to evaluate the effect of loading at three different occlusal surface position of the gold alloy crown on the stress distributions in surrounding bone, utilizing 3-dimensional finite element method. A three dimensional finite element model of an implant with simplified gold alloy crown and supporting bone was developed for this study. A oblique or vertical load of 100 N was applied at the following position at each FE model : 1) center of occlusal surface, 2) a point on the buccal side away from center of occlusal surface (COS) by 2.8mm, 3) a point on the lingual side away from COS by 2.8mm. In the results, Minimum von Mises stresses under vertical load or oblique load of 100N were about 6MPa at the center of occlusal surface and about 40MPa at the point on the buccal side, respectively. From the results we could come to the conclusion that occlusive loading position could be an important factor for establishment of structural safety of supporting bone.

• Journal of the Korean Geotechnical Society
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• v.27 no.11
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• pp.27-37
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• 2011

A series of centrifuge model tests to investigate the suction pile pullout loading capacity in sand have been performed. The main parameters that affect the pullout loading capacity of a suction pile include the mooring line inclination angle and the padeye position of the suction pile. With respect to the padeye position, the maximum pullout loading capacity is obtained when the padeye position is near 75% of the pile length from the top. The direction of the pile rotation changes when the padeye position reaches somewhere near 50~75% for all mooring line inclination angles. The translation displacement of suction pile to develop the time of maximum pullout loading capacity decreased as the mooring line inclination angle increased. In addition, the vertical displacements of the center of a suction piles for all cases appeared to develop toward the ground surface.

• Structural Engineering and Mechanics
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• v.32 no.2
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• pp.337-350
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• 2009

Finite element simulations are increasingly used in structural analysis and design, especially in cases where complex structural and loading conditions are involved. Due to considerable progresses in computer technology as well as nonlinear finite-element analysis techniques in past years, it has become possible to pursue an accurate analysis of the complex blast-induced structural effects by means of numerical simulations. This paper aims to develop a better understanding of the behavior of steel-concrete composite beams (SCCB) under localized blast loading through a numerical parametric study. A finite element model is set up to simulate the blast-resistant features of SCCB using the transient dynamic analysis software LS-DYNA. It is demonstrated that there are three dominant failure modes for SCCB subjected to localized blast loading. The effect of loading position on the behavior of SCCB is also investigated. Finally, a simplified model is proposed for assessing the overall response of SCCB subjected to localized blast loading.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.2
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• pp.103-108
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• 2005

Loading/Unloading task in the real industry is performed by crane, but most of the loading/unloading task with the weight of 5kg∼30kg is done by human workers and this kind of work causes industrial disaster of workers. Therefore it is necessary to develop low cost loading/unloading manipulator system to prevent this kind of industrial accidents. This paper is concerned with the design and fabrication of 2 axis pneumatic manipulators using on/off solenoid valves and accurate position control without respect to the external load and low damping in the pneumatic rotary actuator. To overcome the change of external load, switching of control parameter using LVQNN (Learning Vector Quantization Neural Network) is newly applied, which estimates the external loads in the pneumatic cylinder. As an underlying controller, a state feedback controller using position, velocity and acceleration is applied to the switching control system. The effectiveness of the proposed control algorithms are demonstrated through experiments of pneumatic cylinder with various loads.

• Journal of Dental Rehabilitation and Applied Science
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• v.21 no.1
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• pp.1-14
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• 2005

The purpose of this study was to assess the loading distributing characteristics of implant prosthesis of internal connection system(ITI system) according to position and direction of load, under vertical and inclined loading using finite element analysis (FEA). The finite element model of a synOcta implant and a solid abutment with $8^{\circ}$ internal conical joint used by the ITI implant was constructed. The gold crown for mandibular first molar was made on solid abutment. Each three-dimensional finite element model was created with the physical properties of the implant and surrounding bone. This study simulated loads of 200N at the central fossa in a vertical direction (loading condition A), 200N at the outside point of the central fossa with resin filling into screw hole in a vertical direction (loading condition B), 200N at the centric cusp in a $15^{\circ}$ inward oblique direction (loading condition C), 200N at the in a $30^{\circ}$ inward oblique direction (loading condition D) or 200N at the centric cusp in a $30^{\circ}$ outward oblique direction (loading condition E) individually. Von Mises stresses were recorded and compared in the supporting bone, fixture, and abutment. The following results have been made based on this study: 1. Stresses were concentrated mainly at the ridge crest around implant under both vertical and oblique loading but stresses in the cancellous bone were low under both vertical and oblique loading. 2. Bending moments resulting from non-axial loading of dental implants caused stress concentrations on cortical bone. The magnitude of the stress was greater with the oblique loading than with the vertical loading. 3. An offset of the vertical occlusal force in the buccolingual direction relative to the implant axis gave rise to increased bending of the implant. So, the relative positions of the resultant line of force from occlusal contact and the center of rotation seems to be more important. 4. In this internal conical joint, vertical and oblique loads were resisted mainly by the implant-abutment joint at the screw level and by the implant collar. Conclusively, It seems to be more important that how long the distance is from center of rotation of the implant itself to the resultant line of force from occlusal contact (leverage). In a morse taper implant, vertical and oblique loads are resisted mainly by the implant-abutment joint at the screw level and by the implant collar. This type of implant-abutment connection can also distribute forces deeper within the implant and shield the retention screw from excessive loading. Lateral forces are transmitted directly to the walls of the implant and the implant abutment mating bevels, providing greater resistance to interface opening.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1846-1847
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• 2006

In this study, we developed the real-time controller for control loading system (CLS) of aircraft simulator. The CLS is given the forces as inputs: the exerted force by a pilot, which is determined according to the position of the control stick, and the calculated force by the host computer. And then CLS makes the pilot feel the back loading force by supplying the motor drive with the actuator signal. The developed real-time controller for CLS is organized into the five parts which are the position sensing part including a encoder, the A/D converter part for the analog load cell signal, the communication interface part to communicate with the host, the D/A converter for the actuator signal, and the CPU DSP2812 to carry out a control algorithm. We constructed the test control loading system and carried out the experiment with the developed real-time controller. The experimental results showed that the real-time controller generates the back loading forces similar to the desired back loading force graph.